Ion-selective electrode for transmembrane pH difference measurements

A triethylammonium-sensitive electrode was constructed using sodium tetrakis[3,5-bis(2-methoxyhexafluoro-2-propyl)phenyl]borate as an ion-exchanger and benzyl 2-nitrophenyl ether as a solvent mediator in a poly(vinylchloride) membrane matrix and was used to determine the pH difference across a cell membrane. The method is based on monitoring of the pH gradient-induced uptake of triethylammonium in situ. The triethylammonium electrode exhibited a near-Nernstian response to triethylammonium in the concentration range of 5 x 10(-6)-1 x 10(-2) M with a slope of 58.5 mV per concentration decade in a buffer solution composed of 150 mM NaCl and 10 mM NaH2PO4/Na2HPO4 (pH 7.5). The limit of detection was 1 microM. In experiments using liposomes, the uptake of triethylammonium into liposomes was quantitatively induced according to the pH difference across the liposomal membrane. The transmembrane pH differences in Escherichia coli cells and the light-induced pH differences across the envelope vesicles of Halobacterium halobium were successfully determined by the present method.     

Characterization of a high-brilliance soft x-ray laser at 13.9 nm by use of an oscillator-amplifier configuration

We have improved a highly coherent x-ray laser at 13.9 nm using an oscillator-amplifier configuration. To improve a high-brilliance x-ray laser, we adopted traveling wave pumping for the amplifier target and rotated the amplifier target 3-4 mrad in the counterclockwise direction. Thereby, a seed x-ray laser can be amplified by medium plasma of the amplifier target with a high gain coefficient. The amplified x-ray laser has the output energy of approximately 1.3 microJ, corresponding to a large photon flux of 6.5 x 10(10) photons/pulse and a high peak brilliance of 5 x 10(26) photons/(s x mm(2) x mrad(2) x 0.01% bandwidth).     

Circadian changes in body temperature during the menstrual cycle of healthy adult females and patients suffering from premenstrual syndrome

The biological rhythm of females is closely related to the menstrual cycle, and this rhythm is believed to influence circadian changes in body temperature. This study investigated and compared the patterns of circadian changes in the body temperature of healthy adult females and patients suffering from premenstrual syndrome or major depression. Body temperature was measured both rectally and sublingually in healthy subjects, and only sublingually in the patients. During the luteal phase in healthy adult females, both the average and lowest nocturnal body temperatures increased, the amplitude of the circadian changes decreased, and the times of the lowest and highest temperatures within a 24-hour period were delayed by 2-3 h. In the patients, the amplitude decreased during disease periods, especially in the follicular phase, whereas in the luteal phase, circadian changes showed great variation each day, although the decrease in amplitude was not as remarkable. The results show that (i) the biological rhythm of females is intrinsically unstable in the luteal phase, although this rhythm is stable in the follicular phase; and, (ii) symptoms were often aggravated with the decreases in amplitude experienced in the luteal phase.     

Conjugated polyelectrolyte based real-time fluorescence assay for phospholipase C

A fluorescence turnoff assay for phospholipase C (PLC) from Clostridium perfringens is developed based on the reversible interaction between the natural substrate, phosphatidylcholine, and a fluorescent, water-soluble conjugated polyelectrolyte (CPE). The fluorescence intensity of the CPE in water is increased substantially by the addition of the phospholipid due to the formation of a CPE-lipid complex. Incubation of the CPE-lipid complex with the enzyme PLC causes the fluorescence intensity to decrease (turnoff sensor); the response arises due to PLC-catalyzed hydrolysis of the phosphatidylcholine, which effectively disrupts the CPE-lipid complex. The PLC assay operates with phospholipid substrate concentrations in the micromolar range, and the analytical detection limit for PLC is <1 nM. The optimized assay provides a convenient, rapid, and real-time sensor for PLC activity. The real-time fluorescence intensity from the CPE can be converted to substrate concentration by using an ex situ calibration curve, allowing PLC-catalyzed reaction rates and kinetic parameters to be determined. PLC activation by Ca2+ and inhibition by EDTA and fluoride ion are demonstrated using the optimized sensor.     

Production of highly concentrated xylitol by Candida magnoliae under a microaerobic condition maintained by simple fuzzy control

Microbial production of xylitol from xylose was investigated using Candida magnoliae. In particular, the effect of the oxygenation condition on the xylitol production yield was examined and the significance of maintaining a microaerobic condition was demonstrated. A simple system of fuzzy logic control (FLC) was devised to maintain the microaerobic condition in the xylitol production phase by regulating the proportion of air (air flow rate) supplied to the fermentor. The input variables to the fuzzy control system were the dissolved oxygen (DO) concentration in the culture broth and the CO2 concentration in the exit gas. A batch cultivation test using the FLC system confirmed the importance of maintaining a constant microaerobic condition throughout the xylitol production phase, and indicated it would be advantageous for this phase to be prolonged. An intermittent fed-batch culture was therefore carried out. The FLC system allowed a constant microaerobic condition to be maintained, resulting in minimal cell mass production and constant xylitol accumulation in the culture medium. As a consequence, a very high xylitol concentration of 356 g/dm3 could be attained. The xylitol yield in the fed-batch culture was 0.75, which corresponded to 82% of the theoretical yield.     

Increased epinephrine-induced cAMP response in severely diabetic BB/W rat liver

The effect of prolonged diabetes on epinephrine-induced adenosine 3',5'-monophosphate (cAMP) response in the liver was examined in diabetes-prone BB/W rats. Basal and 1 microM epinephrine-induced cAMP release from isolated perfused liver was similar in non-diabetic and diabetic BB/W rats with preserved adipose tissue. In adipose tissue-absent diabetic rats losing intra- and retro-peritoneal adipose tissue completely, both basal and 1 microM epinephrine-induced cAMP release from the liver were enhanced (P<0.01, each case). Plasma epinephrine and norepinephrine were similar in non-diabetic, adipose tissue-preserved and -absent diabetic BB/W rats. The plasma free thyroxine level was similar in non-diabetic and adipose tissue-preserved diabetic BB/W rats, but was lower in adipose tissue-absent diabetic BB/W rats than in non-diabetic rats (P<0.01), but the frequency of lymphocytic thyroiditis was similar in these three groups, although plasma corticosterone was lower in adipose tissue-preserved diabetic BB/W rats (P<0.05) and the lowest in adipose tissue-absent diabetic BB/W rats (P<0.01). Lymphocytic infiltration was not observed in the adrenal or pituitary glands in any group. Plasma total protein and albumin were low in adipose tissue-absent diabetic BB/W rats (P<0.01, each case). In adipose tissue-absent diabetic BB/W rats, liver dysfunction and hepatomegaly, but no apparent histological change in the liver, were observed. Plasma glucose was higher (P<0.01) and plasma insulin lower (P<0.05) in adipose tissue-absent diabetic BB/W rats than in adipose tissue-preserved diabetic BB/W rats. In conclusion, epinephrine-induced cAMP response in the liver was enhanced only in adipose tissue-absent diabetic BB/W rats. Denervation supersensitivity was not likely to be responsible for the enhanced beta-adrenergic response. The observed reductions in plasma thyroxine and corticosterone seemed to result from severe diabetes. Although the severity of diabetes can vary continuously, severe diabetes with loss of adipose tissue appeared to cause significant changes in the metabolism and enhanced beta-adrenergic response in the liver.     

Isolation and characterization of goldfish Y box protein, a germ-cell-specific RNA-binding protein

Cyclin B is a regulatory subunit of maturation-promoting factor. In goldfish (Carassius auratus) oocytes, cyclin B is synthesized de novo after stimulation by 17alpha,20beta-dihydroxy-4-pregnen-3-one (maturation-inducing hormone). In this study, we examined goldfish oocyte proteins bound to cyclin B mRNA. Using oligo(dT)-cellulose affinity chromatography and northwestern blotting analysis, we identified a 54-kDa cyclin B mRNA-binding protein (p54). Southwestern blotting analysis showed the binding of p54 to the Y box DNA element (CTGATTGGCCAA), suggesting that p54 is a Y box protein in goldfish. We isolated two cDNA clones, GFYP1 and GFYP2, the latter of which encodes a germ-cell-specific Y box protein. An antibody against a GFYP2 protein recognized p54, suggesting that p54 is identical or highly similar to GFYP2 protein. This is also supported by the finding that a recombinant GFYP2 expressed in bacteria bound to both the Y box DNA element and the goldfish cyclin B mRNA synthesized in vitro. These results suggest that p54 is a germ-cell-specific Y box protein and is a potential masking protein of cyclin B mRNA in goldfish oocytes.     

A high-capacitance PZT-on-Ta2O5 memory cell with a chemically stable electrode suitable for sub-micron processing

A high-capacitance Pb (Zrx, Ti1-x)O3 (PZT)-on-Ta2O5 memory cell suitable for sub-micron processing is proposed, and an experimental capacitor of PZT (Zr/Ti= 52/48)-on-Ta2O5 with Ta electrode was prepared. The X-ray diffraction and XMA analysis of the sample showed that PZT reacted with neither Ta nor Ta2O5. The capacitor with 500 nm PZT thickness shows current density of 10-8 A/cm2 at 4MV/cm, the breakdown field of 8MV/cm, and the effective dielectric constant of 40.